Logic / Unit 4 Logic 139 short lesson, about 20 seconds
Tautologies
Captions available
The idea
A tautology is true on every row — true no matter what the world does.
In practice
p ∨ ~p. The store is open or it isn't.
Where people slip
Tautologies are certain and correspondingly uninformative. Certainty is purchased with emptiness.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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